1. Field of the Invention
The present invention relates to a heat-assisted magnetic recording head and a method of manufacturing the same and, more particularly, to a heat-assisted magnetic recording head with which an optical transmission module can be easily integrated and which can easily be changed to have an optical path in a desired direction and a method of manufacturing the same.
2. Description of the Related Art
Previously, it has been difficult to achieve a recording density above 500 Gb/in2 using a conventional magnetic recording method.
In the field of magnetic information recording, many studies have been performed to overcome magnetic recording density limitations and thus achieve such a high recording density.
In order to increase recording densities, a bit size of magnetic recording mediums on which unit information is recorded must be reduced. To reduce the bit size, a grain size of the recording medium must be reduced. Since reduction of the grain size increases thermal instability of a recorded bit, a medium having a relatively high coercive force is necessary.
Since a magnetic field generated by a magnetic recording head and applied to a magnetic recording medium has a limited intensity, it is difficult to record information in a magnetic recording medium when the magnetic recording medium is formed of a material having a relatively high coercive force for providing good thermal stability.
To solve the above problem, a heat-assisted magnetic recording method has been developed, in which a recording medium formed of a material having a relatively high coercive force for overcoming the thermal instability of a small recorded bit is used and heat is locally applied to the recording medium to temporarily lower the coercive force thereof and allow the recording to be performed by a magnetic field applied by a magnetic recording head. That is, according to the heat-assisted magnetic recording method, the coercive force of a local portion of the recording medium is lowered by heating the local portion so that the heated local portion of the magnetic recording medium can be effectively magnetized to perform the recording using the magnetic field applied by the magnetic recording head. Therefore, even when the grain size of the magnetic recording medium is reduced, the thermal stability can be realized.
An optical transmission module that heats a local portion of a magnetic recording medium by emitting light to temporarily reduce the coercive force of the local portion of the recording medium and thus expedite the recording may be applied to a heat-assisted magnetic recording (HAMR) head.
FIG. 1 is a diagram of a conventional HAMR head disclosed in U.S. patent application Publication No. 2003/0198146A1.
Referring to FIG. 1, the conventional HAMR head includes a magnetic recording unit 22 and an optical transmission module for heating the magnetic recording medium 16.
The magnetic recording unit 22 includes a recording pole 30 for applying a magnetic recording field on the magnetic recording medium 16 and a return pole 32 magnetically connected by a yoke 35 to the recording pole 30 to form a magnetic path H.
The optical transmission module heats a local portion A of the magnetic recording medium 16 using a beam of light. The optical transmission module includes a light source 52 and a waveguide 50 for guiding light generated by the light source 52 through an optical fiber 54. An electromagnetic (EM) radiation emission structure 46 is attached to an extreme end of the waveguide 50 near an air bearing surface (ABS) of the magnetic recording medium 16.
The local portion A is located near to the recording pole 30 with respect to the relative motion of the magnetic recording medium 16. As a result, the recording pole 30 vertically records data on the local portion having a coercive force which has been temporarily reduced by heating. That is, magnetic recording can be performed in a state where the thermal instability is solved.
In the above-described conventional HAMR head, the optical transmission module is installed to emit the light to the magnetic recording medium 16 prior to the operation of the recording pole 30. At this point, the waveguide 50 is attached on a side portion of the recording pole 30. As the magnetic recording medium 16 rotates, dynamic air pressure is generated to provide an air-bearing effect by which the magnetic recording unit 22 is floated from the magnetic recording medium 16. At this point, a predetermined gap is maintained between the waveguide 50 and the magnetic recording medium 16.
Since the waveguide 50 collimates an incident light and guides the collimated light to the EM radiation emission structure 46, the optical path is limited to be formed in a predetermined direction. Therefore, the installation position of the light source is limited. The limitation of the installation position of the light source reduces overall design flexibility of the HAMR head as well as an actual manufacturing flexibility.
In addition, since the EM radiation emission structure 46 is separately prepared and attached to an extreme end of the waveguide 50, it is difficult to manufacture the HAMR head through a semiconductor wafer fabrication process.